Pressure actuated signaling device



Oct. 11, 1938. J. E. BRIGG ET AL PRESSURE ACTUATED SIGNALING DEVICE James N. GIbSOTH I nverwtors John E. BM (:5

Filed Aug. 21, 1936 Thelr" Attorrweg.

Patented Oct. 11, 1938 UNiTED STATES PRESSURE ACTUATED SIGNALING DEVICE John Ellwood Brigg and James Nelson Gibson, London, England, assignors to Callenders Cable and Construction Company, Limited, a corporation oi. England Application August 21, 1936, Serial No. 97,290 In Great Britain September 7, 1935 12 Claims.

This invention is concerned with pressure actuated devices of the kind in which variations of pressure or variations of pressure difierence in a fluid pressure system cause movement of a liquid in a U-tube and this movement is caused to give a signal. The reference to giving a signal is here used with a .wide meaning. The effect produced does not necessarily appeal directly or primarily to the senses by visual or audible means. It may, for instance, be the actuation of a relay to close a valve or perform some other action. In order to distinguish between the liquid in the U-tube and the fluid in the pressure system these are hereinafter generally referred to as the U-tube liquid and the pressure fluid respectively.

The invention is concerned with the construction of the pressure actuated device, in such a way that, while the U-tube liquid may be allowed to move freely through a range large enough for the operation of the signal, it is restrained from passing from the U-tube into the external pressure fluid. This restraining eifect is brought about by providing an automatic valve at an appropriate height in a leg of the U-tube, arranged to be actuated to close that end of the U-tube when the U-tube liquid exceeds a predetermined level in that side of the tube. This valve may be used in combination with other auxiliary means to the same'end, iorinstance, with an over-flow chamber to receive and retain any liquid which passes the valve.

In many cases the U-tube liquid will be mercury. The following description deals with the case where mercury in the U-tube co-operates with mineral oil in the external system. From this description the nature of the invention will be readily recognized and it will be understood what modifications, if any, are required to deal with other fluids.

The invention is applicable to one or both of the legs of the U-tube and to cases where the U-tube is replaced by a similar device having more than two legs, this being, in eflect, the combination of two or'more U-tubes.

Under normal operating conditions a considerable length of column of oil will stand above the mercury between it and, the automatic valve. This permits the mercury to move up and down within the usual signalling range so that the -valve need not come into operation except when excessive movement of the mercury is taking place. A convenient form of automatic valve is one in which there is arranged, in a vertical extension of the leg of the U-tube, a conical seating and a ball held normally at a 1 bib low the seating and capable of being lifted by the mercury into contact with the seating although normally held away from that seating by its weight. This arrangement is a float valve dependent for its action on the greater density of mercury as compared with that of the oil. In order to get greater certainty of action of this valve, it is preferred to provide a second float lying below the ball. This may be a hollow cylinder fitting loosely in the tube. This arrangement has the advantage that the lifting effect commences before the mercury has reached the ball so that the risk of the mercury getting past the valve and impeding its closing is greatly reduced. It is preferred to make the seating, the

ball and the float of stainless steel.

As an auxiliary protection, an overflow chamber may be arranged above the valve, for instance, by providing there an enlargement of the tube. This chamberis preferably of sufllcient volume to accommodate the whole of the mercury of the U-tube so that even if it should, in exceptional circumstances, pass the valve it will not travel further.

As an alternative to a float valve, a valve actuated by a relay may be employed. In this case the mercury on reaching an excessive height would bring into action the relay. This may be 7 done by the closing of an electric circuit.

The signalling efiect may also be brought about by the'closing of an electric circuit through the column of mercury. This may, for instance, be done by making the U-tube part of a circuit and intersecting it by a short tube or collar of insulating material in which is embedded a metal contact to which the mercury has access when it passes through the insulating body. Two or more of these contact making arrangements may be included in the same leg of the tube and one of them may be utilized for the valve closing relay oi the tube when this is employed.

An important application of the invention is in connection with electric cable systems in which the strength of the dielectric of the cable is maintained at the desired value by means of mineral oil as a pressure fluid. In such cases it is important that any unusual variation in the pressure of the fluid should be made known by the actuation of an indicator or should be taken care of by the actuation of some automatic control device. The present invention provides a simple device applicable to this purpose while ensuring the prevention of the passage of mercury from the device into the cable system.

' A pressure actuated device constructed in accordance with the invention and intended for use in connection with a three-phase cable system is described hereinafter and illustrated by way of example, in the accompanying drawing,'wherein Figure 1 is a side view of the arrangement partly in section;

Figure 2 is a sectional view of the same arrangement taken on the line 2-2 in Figure 1 and looking in the direction of the arrows, and

Figure 3 is a plan of the arrangement partly in section on the line 33 in Figure 2.

The device comprises three vertical tubes i, joined at their lower extremities by a common horizontal tube 2 to form a three-leg or double U-tube and supported at the upper open ends by a horizontal metal plate 3 provided with suitable apertures to receive the upper ends of the tubes. The system of three tubes contains mercury which under balanced pressure conditions in the fluid pressure system of the cable stands at the same height in each tube l, the lever l of the mercury columns being substantially below the open ends of the tubes. An insulating plate 5, conveniently formed of moulded material, is disposed above themetal plate 3, and thereupon is arranged a second metal plate 6, the two metal plates 3 and 6 and the intervening insulator 5 being held together by bolts 1 passing through the three members. Mounted on the upper metal plate 6 above each tube l is a vertical extension 8, the interior of. which communicates with the interior of the tube l by means of registering apertures 9 and ill formed in the upper metal plate Bend the insulator 5 respectively. Within each extension 8 is arranged an automatic valve which is described hereinafter. Above each extension 8 is arranged an overflow chamber H the volume of which 'is sufficient to accommodate, is necessary, the whole of the mercury in the U- tube system. The interior of each chamber H is joined at the upper end by means of a known,

type of valve l2 to the pressure fluid filled cavity of one of the cable cores of the system. Each chamber is also provided with a T-connection l3, Fig. 2, having a valve l6, similar in construction to the valve l2, which serves for the innel in the cable system through a suitable duct or conduit IS, the end of which is in the form of a conical nipple l6 held against a seating at the entry to the valve l2 by means of a collar ll screwed on to a block l8 closing the upper end of the chamber H. The oil passes thence into the chamber ll through the valve I2 which comprises a-sleeve l9 adapted to slide in the block l8 and to be depressed against the action of a compression spring 20, thereby uncovering a series of small holes 2i, Fig. 2, in the wall of the sleeve l9 through which holes the oil may pass into or out of the chamber H. The compression spring is anchored by a disc 22, perforated topermit the free passage of oil, and restrained against movement into the chamber II by a seating 23 formed on the inner wall of the chamber. In the event of the nipple l6 being removed, for the purpose of disconnecting the cable, the sleeve is is automatically pushed by the spring 20 to its limit into the block l8, whereby the ports are covered and the entry consequently closed.

' The portion forming the chamber II has at its lower end a conical nipple 24 adapted to be held in engagement with a conical seating at the upper end of the passage in the vertical extension 8 by a collar 25 which is screwed on to the end of the extension. Within the interior passage of the extension 8 and directly beneath the upper end thereof is an apertured member 26 located between the lower end of the nipple 2t and a ledge formed on the inside wall of the extension H, and having a conical seating 21 formed on its underside about the aperture. Beneath the seating 27 is a ball 28 normally located at a short distance from the seating 27 on the top of a hollow cylindrical float member 29 which extends almost the length of the extension 8. The ball 28 and cylinder 29 are loosely fitted within the tubular extension and the latter normally rests on that portion of the metal plate 8 which forms a seating for the extension 8 mounted thereon. The apertured member 26, the ball 28 and the cylindrical member 29 form the constituent parts of the automatic valve referred to above, located within the extension 8 and intended to prevent the passage of mercury from the tube i into the cable system. Under normal conditions there will be a freely upwards in front of the rising mercury,

through the automatic valve. If, however, the

The

unbalanced conditions are such that the mercury rises to the cylindrical member 29 the automatic valve operates to prevent the mercury escaping beyond the valve. As soon as the mercury level reachesthe cylindrical member 29, the latter operates as a float and is lifted by the mercury,

thereby at the same time raising the ball 28 until it engages the conical seating 21 thus closing the upper aperture in the extension 8. The valve is thus caused to close by the rising mercury column before the latter actually arrives at the point of escaping from the U-tube system.

The overflow chamber .ll situated above the automatic valve serves as an auxiliary protection to prevent the movement of mercury into the cable system should the automatic valve not function correctly in its primary closing action ,or by permitting subsequently a leakage of mercury. Each chamber II is sufliciently large to accommodate the whole of the mercury in the section of the chamber H the mercury, should it accumulate therein, will not be carried forward beyond that point by the oil, but the latter, having traversed the tube or'tubes' I and displaced mercury, will pass through the mercury in drops or in a more or less continuous stream if the pressure conditions are such' as to produce the movement.

The device is provided with means for closing an electric circuit in the event of the mercury column rising beyond a certain predetermined level in any one of the vertical tubes I. On the upper metal plate 6 and to one side of the arrangement above described, as illustrated in Figures 2 and 3, are arranged four terminals. One terminal 30 is in metallic contact with the plate 6 and consequently by virtue of the bolts 1 andthe' lower metal plate 3, is in permanent electrical connection with the metal mercury-containing tubes l and 2. The stem 33 of each of the other three terminals 3| passes directly through the plate 6 and is insulated therefrom by means of an insulating liner 32 formed integral with the insulating plate 5. Each terminal stem 33 conductively engages a conductive contact strip 34 embedded within the insulator 5 and extending from the terminal to the aperture l whereby the fluid passes through the insulator. The strip 34 completely surrounds the aperture l0 and presents to the fluid passing therethrough a circumferential contact surface 35 which is insulated by the insulating plate from the rest of the mercury-containing system. An external circuit which may contain any desirable indicating and/or controlling means is joined to the terminals by means-of a four core cable 36 led into a suitable box 31 which is mounted on the upper metal plate 6 and encloses the terminals. The box 31 is provided with a cover 38, shown removed in Figure 3, to facilitate access to the terminals and 3|. In the event of the mercury rising in a tube I by such an amount as to come into contact with the exposed part of the contact strip 34, the external circuit will be closed thereby causing to operate the said indicating and/or controlling means.

What we claim as new and desire to secure by Letters Patent of the United States, is,-

1. In combination, a U-tube having three legs united by a common connector at their lower ends and each containing a body of conducting liquid, conduits containing fluid under pressure independently connecting each of the upper ends of the legs to a source of fluid pressure, a valve in each leg of the tube above the liquid therein which is closed by the liquid when it rises above a determined level to prevent the discharge of liquid into the conduits, and contacts connected to circuit wires which are closed by the liquid as it rises a determined amount in any one of the legs of the U-tube.

2. In combination, a U-tube having three legs united by a common connector at their lower ends and each containing a body or conducting liquid, conduits containing fluid under pressure independently connecting the upper ends of the legs to sources of fluid pressure, a float valve in each leg of the tube which is actuated by the liquid therein when it rises above a determined level to prevent the discharge or liquid therefrom into its associated conduit, a chambered receptacle located between each valve and a conduit for receiving any liquid from the leg which may pass the valve, and contacts connected to circuit wires located between the upper end of the tubes and the valves which are closed by the liquid as it rises a determined amount in any one of the legs of the U-tube.

3. In combination, a U-tube having three legs united by -a common connector at their lower ends and each containing a body of conducting liquid, a chambered receptacle connected to the upper end of each of the legs capable of receiving and retaining the liquid therefrom, a conduit connecting each of the receptacles with a source of fluid pressure, an extension conduit connecting each of the receptacles with a tube whereby fluid under pressure may be supplied to said tube and contacts connected to circuit wires located above the normal level of the conducting liquid in the legs of the tube which are independently closed by the liquid in the tubes as it rises above a determined level.

4. In combination, metallic U-tubes having three legs united by a conduit at their lower ends and containing conducting liquid, a metallic support for the upper ends of the legs, a body of insulation mounted on the support, contacts carried by the body having openings registering with the bores of the legs through which the conducting liquid may pass, means containing fluid under pressure independently connecting the upper end of each leg of the U-tube with the duct of a cable, a valve arranged to shut oif communication between each leg of the U-tube and the means, a float actuated by the liquid in each leg as it rises above a determined level to seat the valve, and contacts connected to circuit wires which are closed by the rising of the liquid in any one of the legs of the U-tube prior to acting on the float.

5. A fluid pressure actuated device comprising a U-tube, a column of conducting liquid movable in response to pressure changes therein, electrical contact means responsive to movements of the liquid, and a valve located in the tube above the contact means which is automatically closed by the liquid when it rises above a predetermined height to prevent escape of the liquid from the tube.

6. A pressure actuated device comprising a U-tube, an enlargement at its upper end forming an overflow chamber, a column of conducting liquid in the tube responsive to pressure changes,'the top of the column being normally below the chamber, electrical contact means responsive to movements of the liquid, and a valve located between the contact means and the entrance to the overflow chamber which is automatically closed by the liquid when it rises above a predetermined level normally to prevent the passage of liquid into the chamber.

7. A pressure actuated device comprising a U-tube, a column of heavy conducting liquid therein movable in response to pressure changes, electrical contact means responsive to movements of the liquid, a valve located in the tube above the contact means, and a float riding on the top of the column and located between it and the valve for closing the latter when the level of the liquid in the tube rises above a predetermined height to prevent escape of said liquid from the tube.

8. A fluid pressure actuated device comprising a U-tube, a column of heavy liquid movable therein, an extension for each leg of the tube having a chamber into which the upper end of the tube opens, said chamber being large enough to receive and retain all of the heavy liquid, a body of lighter liquid normally filling the chambers and the portions of the tubes above the heavy liquid, a conduit admitting the lighter liquid under variable pressure to each of the chambers, said lighter liquid in response to changes of its pressure causing movements of the heavy liquid, electrical contact means actuated by the heavy liquid when it rises to a predetermined level, and a float valve located above the heavy liquid in each tube and controlling the opening into the chamber of its said extension, said valves normally being open but closed by the heavy liquid when it reaches a determined high level.

9. A fluid pressure actuated device comprising a U-tube, a column of heavy liquid movable therein, an extension for each leg of the tube having a chamber into which the upper end of the tube opens, said chamber being large enough to receive and retain all of the heavy liquid, a body or lighter liquid normally filling each of the chambers and the portions of the tubes above the heavy liquid, a conduit admitting the lighter liquid to each of the chambers from a source of supply under variable pressure, said lighter liquid in response to changes of its pressure causing movements of the heavy liquid, a branch conduit opening into the chamber for supplying said lighter liquid thereto under' determined conditions, a valve preventing outward flow of liquid from the chamber into the conduit, electrical contact means actuated by the heavy liquid when it rises to a predetermined level, and a float valve located above the heavy liquid controlling the opening into the chamber of the extension, said valve normally being open but closed by the heavy liquid when it reaches a determined high level.

. 10. A fluid actuated device comprising a U- tube having separate legs connected by a conduit at their bottom ends, columns of heavy conducting liquid movablein the tubes, a chambered extension for each of the tubes into which its upper end opens, each of said chambers being large enough to receive and retain any conducting liquid which may be discharged into it by its asso- ,ciated tube, a body of lighter non-conducting liquid normally filling each of the chambers and the portion of the tube above the heavy liquid, c ondui'ts admitting the lighter liquid to the said chambers from separate sources of supply which are independently variableas to pressure, a float valve between each tube and its connected chamber past which the lighter fluid is normally free to flow but which is closed by the heavy liquid in said tube when itrises above its normal working range, and electrical contact means below the aisaiae a second plate located above the first, a body of insulation between the plates, electrical contacts supported by the insulation which are closed and opened by movements of the conducting liquid, an extension for each tube containing a chamber in its upper part to receive the heavy liquid under abnormal conditions, a float in each of the I extensions actuated by the heavy liquid, a stop for each float located above the level of the contacts for limiting the downward movement thereof, a valve located between the upper end of each float and the entrance into the chamber of its extension, a filling of light non-conducting liquid normally filling each of the chambers and the upper ends of the tubes and in which the float is normally submerged, and conduits admitting the lighter liquid to the chambers from separate sources or supply which are independently variable as to pressure.

12. A fluid actuated device comprisinga U- tube, columns of heavy conducting liquid movable in the tubes, a chambered extension for each of the tubes into which its upper end opens, each of said chambers being large enough to receive and retain any conducting liquid which may be discharged into it by its associated tube, a body of lighter non-conducting. liquid normally filling each of the chambers and the portion of the tube abovethe'heavy liquid, conduits admitting the lighter liquid to said chambers from separate sources of supply which are independently variable as to pressure, a valve located between each of the conduits and its chamber which automatically closes when the conduit is disconnected, a float valve between each tube and its connected chamber, past which the lighter fluid is normally free to flow but which is closed by the heavy liquid in said tube when it rises above its normal working range, and electrical contact means be low the valve actuated by the heavy conducting liquid when it rises to a predetermined level.

JOHN mwoon BRIGG. JAMES NmlsoN GIBSON. 

